1. Field of the Invention
This invention relates to a semiconductor motor controlled for energization by a single position sensing element, or reading means, and more particularly, to a semiconductor motor for generating the continuous driving torque by conducting progressively and cyclically the semiconductor switching elements connected in series with the armature coils, through the position sensing signals obtained by a single position sensing element.
2. Prior Art
In general, in operating a motor from a D.C. source, it is conventional to generate the driving torque by effecting the conduction control of transistors connected in series with armature coils through sensing signals obtained by position sensing devices.
Therefore, when the armature coils are for a three phase machine, it is conventional to effect the respective conduction control of the three phase armature coils through three phase position sensing signals obtained by three sets of position sensing elements. In such a case, there are certain shortcomings, that is, since the amount of position sensing elements corresponding to the number of phase are necessary the system may become complex, and since the position sensing element is expensive the system as a whole may be costly. Also in such a conventional system, due to effecting the energization of the armature coil over the angle interval corresponding to the angle width of the magnetic pole, the counter electromotive force may become small at the place of the low magnetic field at both ends of the magnetic pole. Therefore, there will be an additional shortcoming, that is since at the end point an excessive armature current may flow and at that portion the magnetic field is low, the output torque may become small and the efficiency may deteriorate, and moreover the counter torque may mix to produce a revolution irregularity and vibration resulting in the further deteriorating of the efficiency. This shortcoming comes up as a problem particularly in the case of a high output power motor and may even result in not having any utility.